This invention relates to a method of fastening a first shell to a second shell to form a sealed housing.
Devices for fastening shells together have been proposed. They are of the type shown in U.S. Pat. Nos. 3,158,930 and 3,977,299. In these fasteners, a bead on a diaphragm is urged into contact with a preformed shoulder on an annular wall of a first shell. Tabs on a second shell are positioned in slots in the first shell which prevent rotation between the first and second shells. When the tabs engage the bottom of the slots, the annular wall on the first shell is crimped to hold the bead against the shoulder and seal the housing.
As long as the dimensions of the bead of the diaphragm, depth of slots and position of the shoulder are made to specification, this seal is adequate. Unfortunately, tolerances are permitted for each component. If the individual parts are at opposite tolerance limits, an additive effect may occur and under some condition, the seal leaks.